A system and technique for highly controlled thermal and/or ablative therapy of the prostate is proposed. Transurethral and miniature implantable ultrasound therapy applicators, with associated treatment planning and control systems are used to achieve optimal therapy delivery within the prostate gland. Acoustic field shaping and treatment planning are used to achieve treatment of the entire gland, or subregions of the gland. This approach provides for preferential treatment of cancers originating in the peripheral zone, yet can be optimized for disease originating in other zones. The appropriate combinations and positions of probes localize controllable and dynamically adjustable treatment zones. The overall objective is to develop minimally invasive techniques using a combination of transrectal and 2 to 3 miniature ultrasound needle probes for efficacious therapy while sparing the rectum, bladder, and other normal critical tissue structures. PROPOSED COMMERCIAL APPLICATIONS: The outcome of this research could be of immediate benefit in the treatment of prostate cancer with fewer toxicities and morbidity. A large number of eligible patients exists, including those who recur after radiation, those who have extracapsular extension noted following radical prostatectomy, and those who cannot tolerate or select not to have open surgery.